Describe methods of composting and their use/application in horticultural practices.

Describe the importance of the following in the process of composting: choice of material, ratio of green to woody material, aeration, moisture content, lime, pH, temperature, insulation, accelerators, volume, establishment and development.

COMPOSTABLE MATERIAL A good mixture of hard and soft materials; Larger quantities well mixed in; No thick capping layers of one material such as grass clippings; No perennial weeds; No seeding annual weeds; No domestic pet waste.

COMPOSTING PROCESS see mosture, aeration, temperature, materials A good sized heap helps in generating heat and cooking the compost, minimum 1m³ – FILLED IN ONE GO. Are these plastic bins large enough to get efficient composting. Perhaps best used as collecting bins for later amalgamation.

Establishment and Development: Building a compost heap / bin.

Collect a good volume of composting material first, a good mixture; Build heap or fill bin ideally in one go; Layer different materials, alternately green and brown. Chop big items such as cabbage leaves; Soil to provide bacteria; Moisten any dry material and firm down Finish with a insulating layer and waterproof lid Heap will heat up – turn the heap when the temperature starts to fall so that the inner core becomes the outer layer; Repeat turning; When the hot phase has finished the material can be used (as long material) or leave to mature (cold phase). D

CARBON NITROGEN RATIO Ratio of Woody Material to Soft Material: Brown to green/carbon to nitrogen/C to N – for a compost heap to work well this ratio is very important (happy bacteria).
Too high in carbon/hard material – the heap will dry out rather than compost, too high in nitrogen/soft material – acidic fermentation, slimy smelly heap.
The ideal ratio is 25-30 carbon to 1 of nitrogen. Grass clippings ( high N) Straw and chopped dry stalks ( High C) Chopped garden refuse – old bedding, tops of vegetables etc (N) Shredded paper or bark(C)

C TO N RATIO

WOODY TO GREEN RATION

COMPOST AERATION Has to be balance with heat retention. The process of composting a heap should be aerobic as oxygen is needed for the bacteria. Aeration layer at the bottom of coarser chopped stalks or straw. Layering different materials loosely. Do not compact wet grass clipping etc.

AEROBIC COMPOSTING

COMPOST MOISTURE The composting process creates moisture, but if the material is very dry to start with it should be damped down; Lime can be added to the heap to maintain conditions (not acid) as the bacteria like it alkaline.

COMPOST PH Lime can be added to the heap to maintain conditions (not acid) as the bacteria like it alkaline. Compost can get very acid in early stages of composition under 6. An acid compost is usually not finished composting. Usually as the compost finishes the process the pH corrects to between 6.-7.

COMPOSTING TEMPERATURE It used to be thought that aeration of heaps was very important and heaps were built with good air gaps. Now it is recognised that keeping the heat in is also important, so boxes like the New Zealand box are used where the wooden slats are butted up tight. Insulation - an insulating layer (Old carpet?) is put on top of the top layer of composting material and a waterproof lid used to keep rain from cooling the heap. The core of a good heap should reach 60ºC. Commercial green waste temperature varies between 45-90 Centigrade. Weed seeds will be killed off at higher temperatures.

NEW ZEALAND BOX enclosed composting box

COMPOST ACCELERATOR Such as high nitrogen fertilisers ( dried Blood)/ straw pellets/high carbon/dehydrated bacteria (Garotta) can be used, BUT if you get your mixture correct (your C/N ratio) and add some soil to the heap they should not be required. Urine has been used by organic gardeners.

GAROTTA

DRIED BLOOD

Describe the creation of hot beds.

HOT BED Use can be made of the heat from the composting materials. Especially farm animals manure.

Autumn – dig out the soil from a sunken (insulation) cold frame and fill with 45cm of fresh horse manure, compacting as you go and moistening if needed; Put a layer of soil over as a root zone (light texture) 15cm deep when compacted; Heat from the manure will heat the soil as well as the atmosphere of the frame; Allows for the growing of winter crops such as lettuce, or over-wintering of tender plants; Summer use for crops such as courgettes or melons (base will be cool but a rich root zone); Autumn – dig out and use as well-rotted compost.

Below using compost/manure as a heat source - as a propagator:

Long lasting heat source but cools progressively. Hard work to refill each year.

Traditional Pineapple pit using old manure as heat source ( Heligan)

Needs fresh farmyard manure still giving off heat.

PINAAPPLE PIT

Describe composting using wormeries.

WORMERY Adapted dustbin. Uses worms in containers to produce worm cast compost; Compost mostly used to make organic potting compost; Good way of composting a regular but small quantity of waste, such as kitchen waste but can be adapted to a larger scale.

Proprietory product:

Brandling/tiger/compost or manure worm Eisenia foetida:

Bottom drainage layer of gravel/tap or drainage holes 5cm up the sides (tap allows you to drain off liqueur to use as a liquid feed); Partition; Bedding layer of rotted manure/mature compost/sedge peat (NOT moss peat as too acid); Worms; Add food in quarter sections; Food – kitchen waste/garden waste/cold phase compost or manure (paper to reduce wetness); Fill bin to top; Leave bin to mature; Fork through once in a while – getting shallower each time; Harvesting: Remove top layer, half eaten material and use as bedding to start a new container; Dig out compost, removing worms to new bin/store to dry out; Sieve dry compost, removing worms to new bin; Use for potting compost/digging in/top dressing for lawns; For potting compost, use about 40% worm compost mixes with peat/perlite or vermiculite or grit.

WORM BIN

TIGER WORM

BRANDLING WORM

EISENIA FOETIDA

WORM COMPOST

WORM CAST

WORM CAST COMPOST

BLACK GOLD

WORM TEA

Describe the use of composted plant material as a soil improver, mulch, supplier of nutrients.

MULCHING

Quick mulches - Old compost, coarse compost, strawy manure -Can be intended to break down and become Humus over a season. Slow breakdown mulches, Bark, wood shaving, shredded paper, will break down slowly – several seasons but used mostly for annual weed control and prevention of capping of soils. As they break down they will use nitrogen in decay process so reduce fertility temporarily.

Mulching (materials laid over the soil): Conserves moisture; Supresses annual weeds; Provides plant food; Looks nice; Best applied when the soil is moist and warm, usually early April.

Organic Materials: Ideally 10cm deep; Most organics like FYM and compost are good as they provide plant foods but only last a season, with the exception of bark chip which has no food but lasts up to 5 seasons.

Materials laid over the soil; Organic materials ideally 10cm deep; Conserves moisture; Suppresses annual weeds; Provides plant foods; Can look nice; Best applied when the soil is moist and warm, usually early April; Most organics like FYM and compost are good as they provide plant foods, but only last a season, although bark chip has no food but last up to 5 seasons.

Inorganic Alternatives: Polythene (black) needs to be UVI inhibited: Works well; Conserves moisture; Supresses annual weeds and perennials; Black warms the soil; Provides no plant foods; Does not look nice (can be used under a thin layer of nicer looking material such as bark/gravel or cocoa shell); Can puddle as water cannot go through; Holds soil very wet underneath so soil structure is damaged; Long lasting.

Woven Fibres: As polythene but draining and breathable.

Gravel: Looks better, but should be appropriate to surrounding stone. Needs to be thick to stop light going through and allowing weeds to germinate; Not good for small wheels (push chairs); Good over woven fibres; Long lasting.

Glass: As gravel; Brighter colours?? (graveyard look??).

SOIL IMPROVER Compost can be dug into the soil or spread on the surface for the worms to draw down into the soil if a no-dig method is being used. Use after the hot phase as (long) or well-rotted as (short); compost has great physical effect in the soil in improving soil structure. Soil Improvers: Compost can be dug into the soil or spread on the surface for the worms to draw down into the soil if a no-dig method is being used. Use after the hot phase as (long) or well-rotted as (short); compost has great physical effect in the soil in improving soil structure.

COMPOST NUTRIENTS The nutrient content of compost is variable according to the methods of making/ materials used/amount of leaching, etc. Differing amounts given in books: N 1.5-2.5 P2O5 0.2-0.5 K2O 1–2%; N 1.5 P2O5 2 K2O 0.5%; Worm N 1.5-2.2 P2O5 0.8–02.2 K2O 1–1.5%. All levels are low compared with fertilisers’ but the volumes applied make compost a good way of applying nutrients to the soil, particularly when you take into account the fact that compost contains a full range of micro and trace elements.

Describe how to make and use comfrey and nettle tea in order to supply nutrients.

COMPOST TEA

COMFREY TEA Ideally obtain and grow the sterile “Bocking 14” strain.

Steeping method. Fill container (ideally with a tap) with comfrey leaves and apply a weight. Wait 3-4 weeks and it will start to drip. Collect concentrate and dilute to the colour of tea (1 in 10) to use as a liquid feed. Add more leaves as the level falls in the container (a smelly process).

Comfrey is high in Potash for flowering and fruiting plants; (N 0.74 P 0.24 K 1.19%); Nettle is high in Nitrogen to promote growth in plants; Mix the two at the making stage or mix concentrates for a general feed; Both contain trace elements; When finished, empty onto the compost heap and cover (smell).

NETTLE TEA Nettle is high in Nitrogen to promote growth in plants;

BOCKING 14 Sterile stain of comfrey, good for making comfrey tea

State the environmental implications of the above mentioned practices.

ENVIRONMENTAL IMPLICATIONS OF COMPOSTING

environmental implications of the above mentioned practices.

Good recycling of gardening/kitchen waste back into the garden; Saves importing material into the garden that may be contaminated, or involving the cost of transport; Saves on the use of fertilisers with its implication of energy consumption in their manufacture; But Run off/leaked liquid needs to be controlled (can contaminate waterways); Estate sized gardens might need a licence for composting below 1000m³; Hygiene, possible transfer of pathogens? Variable mineral content.